1. Field of the Invention
The present invention relates generally to health care for animals and, more particularly, to diagnostic testing of animal cardiovascular systems for analysis of animal health.
2. Description of the Related Art
In health care services, the job of the veterinarian in determining animal health is made more difficult because the veterinarian's patient cannot describe symptoms and problems. For even the most common ailments, the veterinarian must rely on keen powers of observation. Many tools, diagnostic and/or prognostic parameters, and modalities have been developed for assessment and evaluation of the health status of an animal.
HRV as an Indicator of Health
One of the animal parameters being studied as an indicator of animal health condition is that of heart rate variability (HRV). In general, HRV refers to the variation in the interval between beats of the heart. For example, HRV data can describe the variation in the R-R interval that occur as a normal physiological response, such as the internal response to neuronal or endocrine influences, or variations in heart rate that occur in response to external stimuli. Some studies have shown that HRV data is a non-invasive indicator of the autonomic nervous system (ANS) activity, and an indicator of the sympathetic and parasympathetic influences upon heart beat rate and rhythm.
HRV is relatively well-studied in human medicine, especially with respect to: the respiratory system and its effect on HRV (known as respiratory sinus arrhythmia); cardiac events; the vasomotor system and baroreceptor variation in heart rate and blood pressure (e.g., Mayer waves); the thermoregulatory system; the renin-angiotensin system and the central nervous system. In veterinary medicine, utilization of heart rate variability data for animal health condition assessment is being studied, but useful results have proven somewhat elusive.
HRV in Animal Studies
Some studies have concluded that HRV analysis can provide useful indicators of animal health, while other studies suggest that contradictory or inconsistent results have been obtained. For example, one study concluded that low frequency (LF) components of HRV indicate sympathetic influences on the heart (Rietmann et al., “The association between heart rate, heart rate variability, endocrine and behavioural pain measures in horses suffering from laminitis” (J Vet Med Animal Physiol Pathol Clin Med 2004 June; 51(5) at 218-25)(data recorded from hospital treatment indicated that LF components of HRV represent mainly sympathetic influences on the heart, whereas high frequency (HF) components of HRV are mediated by the parasympathetic tone), whereas another study concluded that HRV was not a reliable indicator (see Houle & Billman, “Low-frequency component of the heart rate variability spectrum: a poor marker of sympathetic activity”, Am J. Physiol. 1999 January: 276 (1Pt2:H215-23)). Thus, proper analysis of HRV data must be carefully performed, with care taken in selecting the proper data parameters to collect and in analyzing the collected data, in order to support valid conclusions about the health of an animal.
It is important that the data collection process itself should be convenient and not overly intrusive to the animal and the owner. Sophisticated laboratory instrumentation systems can collect very precise data streams, but typically they require multiple electrodes and even animal restraints, and the animal being studied may be so upset or hampered by the instrumentation that the collected data is affected and is not reliable. Moreover, the laboratory setting itself is not conducive to collection of valid data from an animal. In addition, unlike humans, most animals are prone to resist cooperating with diagnostic procedures and are not likely to treat equipment with care. To increase the likelihood of collecting valid data, it is important that the data collection mechanism is as minimally intrusive as possible.
Thus, it is important to collect accurate, reliable data of the correct type, to properly analyze the collected data, to draw the right conclusions from the data, and to do so without great inconvenience and without great imposition on the animal and animal owner.
It should be apparent that there is a need for techniques that provide a convenient and non-intrusive means for collecting heart rate data on animals and that collect and analyze proper data parameters and perform appropriate analysis to assess the health and/or condition of an animal under study to assess pain, stress, degree of athletic fitness, fatigue, and systemic compromise. The present invention satisfies this need.